In addition to their use to harvest crops on a farm, harvesters also are used for felling trees and maneuvering logs in forestry applications. They are effective for leveling moderately steep terrain for clearcutting areas of forests. These heavy machines are built on all-terrain vehicles, such as wheeled, tracked on walking excavators. They also may be articulated for turning around obstacles. They are typically used in conjunction with a forwarder, which hauls the logs to a roadside landing.
A typical harvester head consists of: a chain saw; delimbing knives; feed rollers; diameter sensors and a measuring wheel. These functions can be controlled by one operator in the vehicle’s cab. Harvesters are routinely available for cutting trees up to 35 in. in diameter, built on vehicles weighing up to 22 tons, with a boom reaching up to 33 ft. radius. Larger, heavier vehicles do more damage to the forest floor, but a longer reach helps by allowing harvesting of more trees with fewer vehicle movements.